Scandium and thorium are two metals characterized by a high charge to radius ratio. Consequently, they tend to behave similarly in the complexation reactions which are the basis of hydrometallurgical separations. For instance, when scandium is extracted from the solution of tungsten digestion sludge with thenoyltrifluoroacetone (TTA) the only element coextracted in significant amounts is thorium, although more than a dozen other elements are present in the solution. Furthermore, the quantitative separation of scandium from thorium by a simple precipitation or extraction is extremely difficult because of this similarity in the chemical properties of the ions in solution which causes co-extraction. This problem can be dealt with in a satisfactory fashion by the process disclosed here.